Filter device

ABSTRACT

A filter device having a filter housing having at least two housing parts ( 1  and  11 ), which can be separated from one another in order to receive at least one filter element ( 21 ), and which can be connected to one another by means of a coupling device ( 7 ), is characterized in that the respective filter element ( 21 ), or an adapter that can be connected thereto, forms a functionally essential component of the coupling device ( 7 ) such that it is only when the filter element ( 21 ) has been placed in its functional position within at least one of the housing parts ( 1, 11 ) that the respective other housing part ( 1, 11 ) can be connected to this first housing part while forming the filter housing of a functional filter device.

The invention relates to a filter device having a filter housing having at least two housing parts, which can be separated from one another in order to receive at least one filter element, and which can be connected to one another by means of a coupling device.

Filter devices of this type are prior art and are used in a wide variety of fields. In the prior art, such devices are especially widely used in applications for cleaning operating fluids such as hydraulic fluids, fuels or lubricants, coolants and the like. Since the filter devices hereby form important system components, proper functioning and filter performance are a prerequisite for the smooth operation of the respective systems. Taking into consideration the fact that malfunctions, which may include damages and failures, may result in very high costs, the functional reliability of the filter devices represents a significant economic factor. In terms of this problem, the object of the invention is to provide a filter device of the type considered here, which is characterized by a high degree of operational reliability.

This object is achieved according to the invention by a filter device having the features of Claim 1 in its entirety.

An essential feature of the invention is the fact that the respective filter element that is to be accommodated in the filter housing, or an adapter associated therewith, forms a functionally essential component of the coupling device such that it is only when the filter element has been placed in its functional position within at least one of the housing parts that the respective other housing part can be connected to this first housing part in order to form the filter housing of a functional filter device. On the one hand, since in the absence of a filter element, no connection between the housing parts is possible, and without a filter, the filter housing cannot be placed in an operational state, it, is ensured that a filter element is always installed. As a result, there is no risk of a functional failure as a result of operation without an inserted filter element. On the other hand, it is also ensured that only a suitable filter element can be used, which can serve as a component of the coupling device due to the construction thereof. Operation with unsuitable filter elements that do not correspond to the required specifications is thereby excluded.

The coupling device can be advantageously designed in such a way that said device has at least a first connecting element, which is a component of the respective one housing part, and has at least a second connecting element as a component of the respective other housing part, wherein at least a third connecting element is provided, which fixes the two respective other connecting elements to one another as soon as the respective filter element is in a functional position. At the same time, the respective third connecting element can be a component of the filter element and/or a component of the adapter, which, when in its fixed position on the respective two other connecting elements, allows the filter element to be coupled to the adapter at least in the functional position thereof.

In an especially advantageous manner, the respective third connecting element may be a component of the end cap of the filter element, which at least in part comprises the filter element material, wherein the respective third connecting element is disposed such that it is concentric to the longitudinal axis of the filter element.

In the case of especially advantageous embodiments, the individual connecting elements are formed from threads that preferably each have an identical pitch with an identical thread formation. The coupling device with the connecting elements thereof thereby forms a screw connection, so that the connection of the housing parts can be implemented easily and conveniently by means of a screwing process.

In an especially advantageous manner, the respective thread, which forms the third connecting element, can be formed out of plastic, preferably out of the same material as the end cap. In the case of plastic threads thus formed the plastic element of the thread system with which the filter element is associated, and which enters into threaded engagement with the threads of the housing parts, which are usually made out of metal, is replaced each time the filter element is changed. As a result, any kind of plastic including less wear-resistant plastic can be used for the end cap with its threads. In addition, in the case of plastic threads, no metal debris is formed during screwing processes, so that both wear and contamination within the interior of the housing are minimized.

The threads of the first and second connecting elements may be formed having essentially the same length, wherein, in a functional position of the respective filter element, the threads of the respective third connecting element essentially completely cover the respective other threads, which are meshed therewith.

In the case of the standard design of such a filter housing, the configuration may be such that the thread of the respective first connecting element leads to a releasable opening, which is a component of a housing pot as the one housing part, wherein the thread of the respective second connecting element leads to this releasable opening or to the additional housing part adjacent thereto, which is a component of a housing head, which is fitted on the housing pot and connected thereto by way of screwing to close off the opening externally.

In advantageous embodiments, the end cap of the respective filter element has a ring flange, which protrudes outward, and which divides the threads of the end cap into two thread sections, which, when the filter element is in the functional position in the filter housing, the one thread section meshes with the respective one connecting element, and the other thread section meshes with the respective other connecting element, so that the ring flange is in contact with the frontal wall sections of the adjacently disposed housing parts, said wall sections being disposed such that they face one another.

In terms of the design of the end cap, the configuration may advantageously be such that the one or the other thread section leads out to the outside at the upper side or, respectively, at the underside of the end cap.

In especially advantageous embodiments, the one housing part, for example in the form of the housing pot, is provided with a fixing device on the outer circumference thereof for a seal, which is overlapped by wall elements of the respective other housing part, such as the housing head, as soon as the housing parts are connected to one another in their final position, wherein the ring flange of the filter element, when viewed in the longitudinal direction thereof, is disposed above the seal oriented towards an inflow opening of the filter element.

The subject matter of the invention is a filter element, which is preferably provided for a filter device according to one of the Claims 1 to 11 and having the features of Claim 12 in its entirety.

The invention is explained in detail below based on the embodiment illustrated in the Figures. Shown are:

FIG. 1 a longitudinal section of an embodiment of the filter device according to the invention;

FIG. 2 a partial longitudinal section of the filter housing section having a coupling device between the housing pot and the housing head, drawn at a larger scale than in FIG. 1, and

FIG. 3 a broken and cutaway oblique projection of the upper housing part of the embodiment.

The embodiment of the filter device according to the invention shown in its entirety in FIG. 1 has, as a housing part, a housing pot 1 in the form of a circular cylinder that tapers inward slightly towards the bottom 3 of the pot. The bottom 3 is closed except for a centrally located housing discharge element 5, the closing member of which is not shown in FIG. 1. The housing pot 1 is connected at the upper opening 9 thereof via a coupling device 7 to a housing head 11 as the second housing part. The head 11 has connections for the supply and discharge of the appropriate fluids. In the figures, of these connections, only the centrally located inlet is visible, and is labeled as 13. An outlet for the discharge of the filtrate is located laterally on the head 11 and is not visible in the drawing. Fluid passages for the unfiltrate and filtrate are provided in the head 11, of which the fluid passage that is connected to the inlet 13 is formed by an inner cylinder 17 that is concentric to the longitudinal axis 15. The surrounding chamber 19 in the inner cylinder 17 is connected to the filtrate outlet.

A filter element 21 having a conventional, circular cylindrical design can be accommodated in the filter housing, which is formed by the filter pot 1 and filter head 11, which filter element has a hollow cylindrical shaped filter material 23, through which the fluid flows from the inner filter cavity that is surrounded by the filter material 23 and then outward during the filtering process, wherein the fluid passes through a support structure 25 that encloses the filter material 23, which support structure is formed by a perforated shell member or a so-called mesh pack. The filter material 23 is enclosed by an end cap 27 at one end, shown below in FIG. 1. An upper cap end 29 is located at the opposite end of the filter material 23. Both end caps 27, 29 are made of a plastic material, by (means of) injection molding.

The figures show the filter element 21 in its functional position, inserted into the filter housing 1, 11. The inner cylinder 17 of the head 11 overlaps a connecting part on the end cap 29 in order to form a fluid connection between the inlet 13 on the head 11 and the inner filter cavity of the filter element 21. This connecting part is formed by a projection that has the shape of a pipe socket 31, which projects from the flat upper side of the end cap 29, concentric to the axis 15, and which is sealed by a sealing ring 33 on the interior of the inner cylinder 17. The lower end of the pipe socket 31 leads into the inner filter cavity of the filter element 21 that forms the unfiltered side during the filtering process, from which the cleaned fluid passes to the chamber 35 surrounding the support structure 25, which forms the filtered side, after passing through the filter material 23. The cleaned fluid passes from this chamber 35 to the fluid chamber 19 located in the head 11, said fluid chamber being connected to the fluid outlet (not visible) on the head 11.

The upper end cap 29 is designed as a one-piece injection molded part made of plastic, being designed in such a way that it forms an indispensable component of the coupling device 7. This means that, in the case that the filter element 21 having the special end cap 29 is absent, no connection is possible between the pot 1 and the head 11 and therefore the formation of a functional filter housing that is formed from the pot 1 and the head 11 is not possible. In order to form a component of the coupling device 7, the end cap 29 has a disk 37, which encloses the pipe socket 31 and which is flat on the upper side 38 thereof, from the underside of which disk an annular body 39 having a square cross section axially projects. The outer diameter of the annular, body 39 is adapted to the inner diameter of the fluid chamber 19 of the head 11 and the inner diameter of the pot 1 in the region of the opening 9 thereof. The cylindrical inner surface 41 of the annular body 39 overlaps the associated edge section of the support structure 25 of the filter material 23. Gaps 43 are distributed in the annular body 39 such that they are spaced apart from one another as fluid passages between the chamber 35 of the pot 1 on the filtered side and the fluid chamber 19 in the head 11.

A sleeve-like extension 45 is connected to the underside of the annular body 39 of the end cap 29, which extension continues the outer diameter of the annular body 39 and extends axially as a sleeve body that is concentric to the axis 15 having a wall thickness that is slightly reduced towards the free end 47. With the annular body 39 and extension 45, a total axial extension is obtained for the end cap 29, the length of which when measured from the end 47 to the upper side of the filter element 21, corresponds to approximately half of the diameter of the end cap 29. A radial projecting ring flange 49 is located approximately half way along the length between the end 47 and the upper side of the end cap 29. In the case of the functional position of the filter element 21 in the filter housing 1, 11 shown in the Figures, the ring flange 49 is in contact with a wall element 51 on the front surface at the edge of the opening 9 of the pot 1, and with a facing wall element 53 on the front surface on the head 11, when the pot 1 and the head 11 are connected to one another by means of the coupling device 7, see FIG. 2.

On the outside of the annular body 39 and of the extension 45, the end cap 29 forms a connecting element in the form of a thread for the coupling device 7, said connecting element having a first thread section 55 between the lower free end 47 and the ring flange 49, and a second thread section 57 between the ring flange 49 and the upper side of the disk 37 of the end cap 29. Both thread sections 55 and 57 have approximately the same length and are formed by an external thread having the same thread formation and pitch. A further thread 59 is formed on the interior of the pot 1, connecting to the opening 9, as an additional connecting element of the coupling device 7, and a thread 61 is located on the head 11, extending from the wall element 53 at the front side, as an additional connecting element of the coupling device 7. These threads 59 and 61 likewise have the same thread formation and pitch as the threads formed by the thread sections 55 and 57 on the end cap 29, wherein the axial length of the threads 59 and 61 are each formed by an internal thread on the pot 1 or, respectively, head 11.

In the case of this configuration, the coupling device 7 only allows a screwed connection between the pot 1 and the head 11 in the case that the filter element 21 has been inserted into the housing 1, 11. The insertion process may be carried out in such a way that the filter element 21 is screwed with the thread section 57 of the end cap 29 into the thread 51 in the head 11 until the ring flange 49 on the wall element 53 abuts the head 11. The unit comprising the head 11 and filter element 21 thus formed can now be connected to the pot 1 in that the thread section 55 on the extension 45 of the end cap 29 is screwed into the thread 59 of the pot 1 until the ring flange 49 abuts the wall element 51 of the pot 1 on the front surface. As the Figures show, in the screw connection that is formed, the threads 59 and 61 on the 1 or, respectively, on the head 11 are essentially completely covered by the thread sections 59 and 61 of the end cap 29.

In order to form a seal between the pot 1 and the head 11 of the housing when the screw connection has been formed, an annular groove 35 is formed on the outside of the pot 1 in the wall region adjacent to the opening 9, in which groove a sealing element 67 is incorporated. An axially projecting external ring 69 is located on the facing edge of the head 11, said external ring being radially offset radially outward vis-à-vis the thread 61, the inner wall of which external ring overlaps the sealing element 67 in order to form the seal with the pot 1 by means thereof. 

1. A filter device having a filter housing, which has at least two housing parts (1 and 11), which can be separated from one another in order to receive at least one filter element (21), and which can be connected to one another by means of a coupling device (7), characterized in that the respective filter element (21), or an adapter that can be connected thereto, forms a functionally essential component of the coupling device (7) such that it is only when the filter element (21) has been placed in its functional position within at least one of the housing parts (1, 11) that the respective other housing part (1, 11) can be connected to this first housing part while forming the filter housing of a functional filter device.
 2. The filter device according to claim 1, characterized in that the coupling device (7) has at least a first connecting element (59), which is a component of the respective one housing part (1), and has at least a second connecting element (61), which is a component of the respective other housing part (11), and has at least a third connecting element (55, 57), which fixes the two respective other connecting elements (59, 61) to one another once the respective filter element (21) is in functional position.
 3. The filter device according to claim 1, characterized in that the respective third connecting element (55, 57) is a component of the filter element (21) and/or a component of the adapter, which, when in its fixed position on the respective two other connecting dements, allows the filter element (21) to be coupled to the adapter at least in the functional position thereof.
 4. The filter device according to claim 1, characterized in that the respective third connecting element (55, 57) is a component of an end cap (29) of the filter element (21), which at least partially comprises the filter element material (23), and in that the respective third connecting element (55, 57) is disposed such that it is concentric to the longitudinal axis (15) of the filter element (21).
 5. The filter device according to a claim 1, characterized in that the individual connecting elements are formed by threads (55, 57, 59, 61) which preferably each have an identical pitch with an identical thread formation.
 6. The filter device according to claim 1, characterized in that the respective thread (55, 57), which forms the third connecting element, is formed. out of plastic, preferably out of the same material as the end cap (29).
 7. The filter device according to claim 1, characterized in that the threads (59, 61) are formed by the first (1) and second connecting elements (11) essentially having the same length, and in that in the functional position of the respective filter element (21), the threads (55, 57) of the respective third connecting element essentially completely cover the respective other threads (59, 61), which are intermeshed.
 8. The filter device according to claim 1, characterized in that the thread (59) of the respective first connecting element (1) leads to a releasable opening (9), which is a component of a housing pot (1) as the one housing part, and in that the thread (61) of the respective second connecting element (11) leads to this releasable opening (9) or to the additional housing part adjacent thereto, which is a component of a housing head (11), which is fitted on the housing pot (1) and connected thereto by way of screwing, to close off the opening (9) externally.
 9. The filter device according to claim 1, characterized in that the end cap (29) has a ring flange (49), which protrudes outward, and which divides the threads of the end cap (29) into two thread sections (55, 57), of which, when the filter element (21) is in the functional position in the filter housing (1, 11), the one thread section (55) meshes with the respective one connecting element (59), and the other thread section (57) meshes with the respective other connecting element (61), so that the ring flange (49) is in contact with the wall sections (51, 53) of the adjacently disposed housing parts (1, 11), the front surfaces of said wall sections being disposed such that they face one another.
 10. The filter device according to claim 1, characterized in that the one or the other thread section (55, 57) of the end cap (21) leads out to the outside at the upper side or, respectively, at the underside of the end cap (21).
 11. The filter device according to claim 1, characterized in that the one housing part (1) is provided with a fixing device (65) for a seal (67) on the outer circumference thereof, which is overlapped by wall elements (69) of the respective other housing part (11) once the housing parts (1, 11) are connected to one another in their final position, and in that the ring flange (49) of the filter element (21), when viewed in the longitudinal direction thereof, is disposed above the seal (67) oriented towards an inflow opening (31) of the filter element (21).
 12. A filter element, preferably provided for a filter device according to claim 1, having at least one end cap (29), which at least partially encloses a filter element material (23), characterized in that the end cap (29) has at least one connecting element (55, 57), which can be connected to other correspondingly formed connecting elements (59, 61) of a filter housing (1, 11) in such a way that only such a filter element (21) can be exchanged within the housing (1, 11) and can be placed in an effective functional position for the filter device. 